PTL1 discloses an invention of dynamically distributing data in units of files to volumes having reliability properties and performance properties appropriate to the files in a file system and a network attached storage (NAS) system configured to distribute and store data into a plurality of volumes. In order to optimize data storage destinations and to save the trouble of setting the distribution by an operator, the invention includes: in response to a user input by or the like, creating storage requirement calculation rules in which a reliability requirement and a performance requirement are set for each type of business application; creating storage destination volume calculation rules in which a reliability requirement and a performance requirement are set for each storage destination volume attached to a group of secondary storage devices; acquiring the reliability requirement and the performance requirement by searching the storage requirement calculation rules by using the file type (business application) as a key; acquiring a storage destination volume by searching the storage destination volume calculation rules by using the acquired reliability requirement and performance requirement as keys; and storing the file in the acquired storage destination volume.